1. Field of the Invention
This invention relates to a method or apparatus for treating with treating liquid such as plating liquid the inside surface of cylinders of a work provided with at least two cylinders such as engine blocks, and in particular, to such a method or apparatus allowing for treating the inside surface of cylinders having different axial alignments, using a flowing liquid system at a high productivity.
2. Background of the Art
Various technologies for treating the surface of a work, such as plating and degreasing prior to plating, are hitherto known. For example, immersing methods adapted for plating and the like, in which a work is immersed in a treating liquid stored in a tank, are commonly conducted; however, in the methods, treating time is extremely long, and productivity is low. Thus, a method which allows for high speed treatment with an improved efficiency by flowing treating liquid relative to the surface of a work to be treated has been recently developed. Such an apparatus is characterized in plating treatment of the inside circumferential surface of a work having a cylindrical portion by permitting treating liquid to flow over the surface. In the apparatus, a passage-forming cylindrical member is mounted on a work-gripping member of a workstation, in which the passage-forming cylindrical member is being inserted into a cylinder of a cylinder block which is placed on the workstation. By permitting treating liquid to flow between the outside circumferential surface of the passage-forming member and the inside circumferential surface of the cylinder, an intended surface treatment such as plating treatment can be efficiently conducted on the inside wall of the cylinder.
However, in the above apparatus, when the passage-forming member is affixed to the work-gripping member, it is difficult to adapt the above apparatus for cylinders, each having the axial center slanted at a given degree from the axial direction of the cylinder block, such as a cylinder block of a V-shaped engine, since a structure in which each passage-forming member can be placed inside each cylinder without interruption cannot be readily constructed. For this reason, when a work is a cylinder block such as that of a V-shaped engine having circumferential surfaces having at least two different axial alignments, it is difficult or impossible to treat all of the circumferential surfaces without interruption. Further, an apparatus adapted for a work having cylinders with a single axial alignment cannot be readily employed for a work having cylinders with different axial alignments, since the center of balance of the work is not aligned with the axial alignments of the cylinders, thereby making it difficult to secure the work on a workstation.
In addition, in the aforesaid apparatus, the end of the cylinder opposite to the end in which an electrode is inserted is simply closed with a closing member covering the end from the outside. However, in many cases, covering the end from the outside is not sufficient to fully seal the end. In the case of a high speed flowing system, the closing member is especially prone to leaking of treating liquid. Further, when a projecting step such as a crankshaft bearing portion is formed inside the cylinder surface at the end, it is difficult to seal an airtight cover at the end of the cylinder.